Automatic control



NOV. 9, 1937. NEUMAN 2,098,591

' I AUTOMATIC CONTROL.

Filed Jan. 15, 1936 any u Patented Nov. 9, 1937 UNITED STATES.

PATENT OFFICE aosasar Au'rom'rrc common Jacob J. Neuman, Jamaican. ,Y. Application January 1a, 1936, Serial No. 58,804

' 4 Claims. (01. 127522) to run this hot water into the screw conveyor instead of adding it at the melter, some very definite advantages would be obtained.

First, the sugar would be mixed thoroughly in the screw with the water and thereby relieving the duty on the melter.

Second, the sugar being mixed with the hot water in the screw will run freely and require less than one tenth of the power to operate the screws.

In the past, it has been attempted to accom-' plish this'by manual control but with very unsatisfactory results due to the fact that at times insufiicient water was applied and then the power would be greater than with no water application, as the sugar would get into a form similar to a bakers dough or paste, then at other times, too much water would be applied, which is very unsatisfactory for the melting.

An object of the present invention is, therefore, to. provide means for adding water to the sugar in the conveyor in amount sufllcient to make it run freely and begin the dissolving.

Another object is to control the addition of water by the load imposed on the conveyor motor.

A further object is to make such control automatic to free it from human error and to reduce the number of attendants required.

Another object is to maintain a substantially constant density in the solution delivered to .the melter. H

A still further object is to provide an electric controlling apparatus by means of which the other objects are carried out.

Yet another object is to use-in this electric apparatus a magnetic relay possessing the following features: adjustable to operate at various current values; an adjustable core to alter the magnetic flux; a by-pass device for temporarily short circuiting the magnetic flux; an arrangement whereby two circuits may be controlled processes" succeeding the simultaneously by the relay; 9. further arrangement for controlling two circuits wherein one is opened or closed before the other.

In the drawing wherein the same numbers refer to like or corresponding parts,

Figure -1 is a side elevation of a unit employing the present invention, with the circuits shown in diagram and parts in section.

Figure 2 is an enlarged detail side elevation of the relay control for the sweetwater, with part of the coil broken away. a

Figure 3 is a top plan view .of the same relay, and

Figure 4 is a sectional fragment taken on the line 4-4 of Figure 2.

In Figure 1, the centrifugal extractor Ill, having a revolving basket ll driven through a shaft I2, is suspended over the screw conveyor l3 which carries sugar to the melter tank M. The screw conveyor I3 is composed of a tube [4 within which is mounted the screw l5 driven by the motor l5 through the reducing gears II. V

In the upper end of the conveyor tube I4 is located a spray head 18 for the purpose of adding melting water to the sugar in the conveyor IS. The spray I8 is connected with a watersource through the magnetic valve l9 which is controlled by the relayT2ll in the circuit of the motor I6. Electric current for the motor I6 is drawn from the supply line. 2| thru the leads 21'- and 2 l and controlled by the motor switch 22.

In operation the extractor l0 builds up a wall of sugar 23 on the sides of its basket II. This accumulation is removed and permitted to fall into the conveyor 13 where it is mixed. with water entering through the spray l8 andcarrled to the melting tank l4. At the melting tank I4 the sugar. and water are heated by steam or other coils 24 and agitated by a motor driven paddle 25 to complete the dissolving, after which the solution is removed and the sugar continued through theremaining steps of the process.

This invention concerns particularly the automatic control of the melting water sprayed into the conveyor 13. As the sugar accumulates in the extractor Ill the switch M is closed starting the motor l6 and drlving'the screw 15.

The

relay 20 is normally closed energizing the solenoid 25 of the, wateryalve l9 and closing the same. This relay 2!! has a predetermined operating range so that at low current values in the motor circuit the switch 20 remains closed but at a. definite higher value the switch 20 opens.

As the dry sugar enters the conveyor- IS the screw l5 'meets increased resistance and the motor l6 draws more current. The added current flowing through the relay 20 causes the opening of the circuit through the solenoid 26 allowing the valve l9 to open under the force of its spring 21 thus admitting water to the conveyor I 3. As water is mixed with the sugar the resistance of the screw l5 dropswith a consequent drop in current passing through the motor I6. As the current drops below the minimum required to open the relay 20, it closes again completing the circuit through the solenoid 26 and closing the valve l9.

The relay 20, which is in the motor circuit, is of the electromagnetic type, the primary circuit being through the coil 28, and the secondary being controlled by a mercury switch 29, as shown in detail in Figures 2, 3 and 4.

The coil 28 is held in a soft iron cap 30 by a bottom plate 3| of some non-magnetic material such as brass. The top of the cap 30 is drilled and tapped over the hollow core portion of the coil 28 to receive the threaded soft iron core piece 32. which is thereby adjustable in the core to vary the effect of the magnet. A locking nut 33 is provided to hold the core piece 32 in adjustment.

The mercury switch 29 is suspended at the bottom of the magnet by the usual form of brass bracket 34, carrying clips 35 adjustable with respect to the magnet by movement in the slots 36 of the bracket 34. The mercury switch 29 employed comprises a glass tube 31 having a mercury wellv38 at each end, and a wire 39 of a magnetic material bridging the wells 38. The magnetic field is concentrated beneath the coil 28 by the use of a small iron core piece 40 in the lower part of the hollow core and resting" on the plate 3|. A bar 4i, likewise of a magnetic material, is held against the underside of the plate 3| by bolting to the small core piece 40 by a steel screw 42, the magnetic field being thus concentrated in the bar 4|.

By adjusting the magnet strength, by moving the core piece 32, and also by moving the mercury tube 29 to or away from the bar 4|, the

point at which the valve l 9 is opened and water admitted to the conveyor l3 may be varied. For accomplishing a temporary shorting of the magnetic fiux a threaded soft iron plunger 43 is passed through the side of the cap 30 and the plate 3| extending inward towards the bar 4|. At the outside of the cap 30, the plunger 43 is provided with a non-magnetic head 44 affording a means for rotatingthe plunger 43 to cause it to short circuit more or less of the magnetic flux to the cap 30 thus raising the minimum. current required to lift the wire 39. Its purpose is to short circuit a portion of the magnetic flux. When motors and conveyors start up they are cold and draw more current for several hours until warmed up. By pushing in the plunger 43 a portion of the magnetic-flux is bypassed between the cap 30 and the bar 4| and the switches 29are thus not operated as'would normally be the case when a current passed which is in excess of that for which the core piece 32 has been adjusted. After the machine is warmed up and drawing normal current the operator pulls out the plunger 43. Spacing washers 45 are placed between the head '44 and the cap wall 33 to limit the extent of inward movement of the plunger 43. The washers 45 are added in sufllcient number to permit the plunger 43 to be pushed in enough to bypass a portion of the flux just sufilcient in quantity to prevent the relay 2!) from operating at the normal current during the warm up period. If too much were bypassed the relay 20 might fail to operate even at a serious overload.

Figures 3 and 4 show a modification in which two mercury switches 29 are used. The relay 20 in such a case may be used as a two pole single throw switch and so may control two circuits. The circuits will be controlled simultaneously ii similar mercury tubes 31 are used and they are held at the same distance from the bar 4!. It may be of value to have one circuit open before the other, in which case the bar ii will be provided with a stepped portion 46 as shown in Figure 4 so that one oi. the supporting brackets 34 will be lower than the other and the mercury tube 31 will be correspondingly removed from the magnetic field with the result that a stronger field will be required to open it.

The relay 2!! is adjusted as follows: With the coil 28 in the motor circuit connected to the leads 2| and 2|, the core piece 32 is screwed retract the core piece 32 a turn or so to allow a slight excess 01 current without operating the relay 20. This margin of excess is best determined by trial for the individual case. When the core 32 is properly adjusted the lock nut 33 is tightened to prevent further motion.

It is obvious that various changes and modifications may be made in the details of construction and design of the above specifically described embodiment of this invention without departing from the spirit thereof, such changes and modifications being restricted only by the scope of the following claims.

What lag-claimed is: v

1. An automatic sweetwater control for an electric motor driven conveyor and screw having an electromagnetic valve for said sweetwater and a relay to control said valve in series with said motor, said relay including a primary coil in series with the motor, and a magnetic mercury switch suspended beneath said coil and adapted to be opened when suflicient magnetic fiux is induced ,in said coil, said switch controlling said electromagnetic sweetwater valve to open the same when due to increased resistance in the conveyor screw the motor draws a current higher than that normally drawn.

2. In a sugar refining apparatus a source of sugar, an electric motor driven screw conveyor for the sugar, 8. water delivery means in the conveyor for adding melting water to the sugar, a receiver for the sugar and water mix, an electrically controlled valvefor the water delivery, an electromagnetic relay for said valve control, said relay comprising a primary circuit coil in series in the conveyor motor circuit, an adjustable core piece in the coil for varying the magnetic flux of the coil, a magnetic switchrcontrolling the secondary circuit and adapted to be opened by the Iorceorthe coil, and a bypassing means for temporarily short circuiting the magnetic flux when the conveyor motor is cold and draws a current higher than the normal?" 3. In a 1 sugar refining apparatus, a sugar source, a mixing member, means conveying the sugar from the source to the mixing member, operating means for said conveying means, water discha ing means associated with said conveysugar from the source to the mixing member,

operating means for said conveying means, water discharging means associated with said conveying means, and electrically operated control means connected with said operating means and said water discharging. means to automatically turn on or cut of! the water discharge means dependent upon the resistance of the movement of the sugar on said conveying means.

' JACOB J. NEUMAN. 

